What IS that? Mysterious 15 metre-long slimy sea creature is found washed up on a remote Indonesian beach.

The rotting remains of a mystery sea creature have washed up on a remote Indonesian beach.

The amorphous carcass – measuring around 15metres long and several metres wide – was discovered by local resident Asrul Tuanakota on the northern shore of Seram Island in Maluku province, the Jakarta Globe reports.

Mr Tuanakota, 37, initially thought the huge sea creature was a stranded boat when he found it on Tuesday night.

The rotting remains of a giant sea creature washed up on a remote Indonesian beach on Tuesday

The 15m carcass was discovered by Asrul Tuanakota, a local resident, on Seram Island

Since then, residents have flocked to Hulung Beach to see the bloated and discoloured mass for themselves.

Baffled locals have speculated that the creature may be a giant squid or the remains of a whale.

Residents have asked authorities to help remove the decaying remains.

Earlier this year, a mysterious hairy sea monster was found on a beach in the Philippines.

It baffled locals who speculated the two-tonne creature was a kind of rare undiscovered dugong.

It was later identified as a whale – but had developed a strange appearance due to decomposition.

Giant mystery sea creature washes up on remote beach in Indonesia.

The creature is thought to have been dead for at least three days before it was found.